7
unrequited
6
unpaid(adjective, free, settled, voluntary, taken)
5
due(adjective, money, immoral, settled, unpaid)
5
outstanding(adjective, weak, poor, low, referring)
5
overdue(adjective, late, behind)
3
owing
2
gratuitous
2
payable(adjective, settled)
2
unprofitable
1
buckshee
1
complimentary
1
costless
1
free
1
gratis
1
indebted
1
nonprofessional
1
owed
1
rent-free
1
uncompensated
1
undischarged
11 years ago|639 views|share |citing 
APASmart Define. (2015). paid thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/paid/thesaurus/antonyms
ChicagoSmart Define. 2015. "paid thesaurus" https://smartdefine.org/paid/thesaurus/antonyms (accessed September 27, 2026).
HarvardSmart Define 2015, paid thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/paid/thesaurus/antonyms>.
MLASmart Define. "paid thesaurus" 1 October 2015. Web. 27 September 2026. <https://smartdefine.org/paid/thesaurus/antonyms>